This invention relates to a roller system for flattening irregularly shaped pieces of scrap sheet metal that are generated during the manufacture of stamped metal parts or other metal forming operations. Such scrap sheet metal pieces are typically re-used or recycled by melting the pieces in a furnace and, thereafter, forming new metal sheets from the melted metal. Ordinarily, scrap metal of the type that is left over from stamping or cutting away portions of a larger metal sheet, is bent in three planes and is irregular in size and shape. Thus, pieces of such scrap are difficult to handle. Moreover, those bent scrap pieces are bulky. Therefore, collections of loose pieces require considerable space to transport them from the scrap generating source, such as a stamping press, to a remotely located melt furnace.
In the past, to reduce the volume of a collection of the loose, pieces, the pieces have been tightly compacted together into large, bulky blocks or bales for transport from the generating source or factory to the recycling furnace facility. Because of the irregular shapes and bends of the loose pieces, transporting them in large containers or by trucks requires considerable space. Compressing the pieces into a compressed mass substantially increases the amount of material that can be loaded into a container or truck, which substantially reduces the costs of transportation. However, a substantially solid block or bale is more difficult to melt when dumped into a melt furnace. The difficulty arises because individual pieces melt faster since their surfaces are directly exposed to the heat energy. In the case of a compressed block, the exposed surface areas are limited so that more time and heat energy is required for the heat to penetrate and melt the compacted block.
Thus, on the one hand, it is desirable to feed the separate pieces of scrap sheet steel into the melt furnace so as to more quickly expose their surfaces to the heat energy for more rapid melting. But, on the other hand, moving the collection of loose individual pieces to the furnace requires so much more transportation space than a compacted block-like mass. Consequently, it would be desirable to flatten the bent sheets so that they require less space for transporting them while they remain separate for loading them into a furnace.
Attempts have been made in the past to provide equipment which will rapidly and inexpensively flatten irregular and bent scrap sheet metal pieces to decrease the amount of volumetric space needed for transportation of large quantities of scrap pieces. Flattened pieces substantially reduce the volume of individual scrap metal pieces so that they may be loosely transported, such as in a large bin, without compacting them into a large block or blade.
An example of prior flattening equipment is disclosed in my U.S. Pat. No. 4,739,641 issued Apr. 26, 1988 for a “Process And Apparatus For Flattening Sheet Gauge Metal Scrap.” The equipment and process disclosed in that patent flattens irregularly size and shape and multiply bent scrap pieces by moving and squeezing the pieces through the nip of a pair of aligned rollers. Thus, those pieces may be transported loosely in bins or other containers without compacting them into conventional, large compressed blocks.
However, a problem which arises from time to time with that type of roller flattening equipment, is that pieces of the scrap fed into the space between the rollers sometimes will clump or entangle together. That may jam the rollers or block further feed into the nip between the rollers. Breaking up the blockage requires an attendant to separate the two rollers sufficiently to enable the entire clump to pass through the nip between the rollers without any flattening of those pieces. When such clumping occurs, particularly at unexpected moments, the attendant must be alert and available to immediately separate the rollers to clear the blockage. In that event, separating the rollers involves moving one roller away from the other to momentarily enlarge the gap between the rollers. After the clump of entangled unflattened pieces pass through the widened nip, the rollers must be restored to their operating positions where they are again close to each other. During the separation of the rollers, the feed of incoming scrap must be turned off momentarily to prevent the passage of a significant number of unflattened, separate pieces along with the clump.
In addition, there are times when the rollers become slippery due to the accumulation of oil or other lubricants carried to the rollers by the scrap metal. Lubricants are normally applied to the surfaces of sheet metal when the metal is stamped or cut prior to the formation of the scrap pieces. When that happens, pieces of sheet metal that pass into the space between the adjacent rollers tend to simply slide around above the flattening gap between the rollers and fail to pass through the gap. The pieces may remain upon the slippery surfaces of the rollers above the gap or nip until an attendant physically forces the pieces through the narrow gap or nip. That slows the automatic flattening operation and requires manual attention. If the roller surfaces become too slippery, it is necessary to shut down the system and to clean the roller surfaces so as to enable sufficient friction to be developed between the rollers and the scrap metal pieces for drawing the scrap metal through the nip.
Thus, this invention is concerned with improved flattening equipment, which utilizes a pair of flattening rollers for squeezing the irregular, bent or contorted pieces of sheet metal, by reducing clumping of the pieces and hold-back or flow interruption resulting from the slipperiness of roller surfaces which reduces the needed friction for driving the pieces through the nip or gap between the rollers. Moreover, this invention is concerned with providing increased compressive forces which will better and more quickly flatten conventional scrap sheet metal pieces.